Electrical discharge apparatus



INVENTORS ATTORNEY Oct. 9, 1934. c. T. ULREY ET AL ELECTRICAL DI SCHARGEAPPARATUS Filed Nov. 1, 1952 Patented Got. 9, 1934 ELECTRICAL DISCHARGEAPPARATUS Clayton Tridle Ulrey, East Orange, and Norman I 0. Beese,Verona, N. J., assignors to Westinghouse Lamp Company, a corporation of-Pennv sylvania Application November 1, 1 932, Serial No. 640,632 .11Claims. (01. 250-35 This invention relates to electric discharge devicesembodying means adapted to indicate the condition and especially thethermal characteristic of some constituent thereof. In its more 5specific aspect the invention is directed to an X-ray tubeembodyingmeans adapted to apprize an operator thereof of the thermal condition ofthe anode and especially that portion. of the anode embodying the X -rayemanating target.-

Generally, electrical devices, such. as X-ray tubes, comprise anevacuated envelope having a plurality of oppositely disposed electrodeslocated therewithin. Qne of these electrodes, termedthe cathode, iscommonly in the form of a filament. 'This filament has its terminalsconnectedto the secondary winding of a low voltage transformerfrompwhich it obtains electrical energy which heats the filament toincandescence, and thermionically active temperature.

erally comprises a metallic rod, such as copper or The other electrode,termed the anode, genthe like, having embedded in theend thereofopposite the, cathode-a discv or plate of an X-ray emitting material,such as tungsten or the like.

When a voltage is applied between the cathode and the. anodetheelectrons emitted at the ca thode due to its temperature are caused.to mi,- grate from the cathode andbe directed upon'the tungsten targetwith sufficient. velocity to cause X-ray emanations from. said target.The type of X-rays thatemanate from the target may be hard or softX-rays depending upon the magnitude of the voltage applied between theelectrodes;

. In practice it has been found ,thatthe target becomes heated due tothe'electrons impinging thereon and that when some X-ray tubes areoperated over an extended period of. time'that the target itself maybecome heated to such an extent and its temperature raised to such adegree that fusion thereof results;

Target heating and overheating with the consequent fusion thereof hasheretofore been appreciated and known to thoseiskilled in the art. Inorder that overheating with the consequent fusion of the target might beobviated it is sometimes necessary that the voltage between the anodeandcathode be. removed. At such times when the operation ofan X-ray tubeover an extended priod of time is-desired there is no clear, simple andinfallible, visible or other mleans in an X.-ray apparatus which wouldindicate that,

the temperature of thetarget is in the vicinity of. its criticaltemperature, the fusion pointthereof.

might readily ascertained so that the necessary steps maybe takentoobviate ,target'fusion it hasheretofore been proposed by Ulrey, in hisPatent 1,704,267 issued -March 5, 1929 which. patent is assigned to thesame assignee asthe present, invention, to employ in combination with.an X-ray tube'a thermo-couple comprisig a plu' ralityof conductorscomposed of dissimilar metals united at one end. This thermo-couple extends within the envelope of the X.-ray tube and has its-junctionembedded in the anode at a position in the" vicinity: of the.target'embedd'ed saidanode. I. Although this heretofore proposedconstructionhad admirably served the purpose for which it was intended,we have in the course; of our experimentations'in this field developedthepresent inventionwhich is a substantial improve-f ment over thathereinbefore briefly described.

Our invention contemplates the provision of an Xeray tube embodying a'thermo-co'uple which construction employs the anode as one of. theelements of a thermo-couple; which construction maybe readily,expeditiouslyand'inexpem sively manufactured; which construction issimpler and has fewer parts than the constructions heretofore proposed;which'construction is more attractivethanthose heretofore proposed 'andwhich construction in spite of having fewer'parts' at least as.sensitive and; enables one to obtain; as true an indication of thetarget temperature as'those heretofore'proposed for the same generalpurposes. a

Brieflystated our invention contemplates the provision of asingle'additional wire'as one of the elements of a thermo-couple withinthe envelope' of an ordinaryiX-ray tube, and the utilization of theanode'per se and the anode extension as the other element of thethermo-couple. Thus the anode and anode extension perform dualfunctions. They together serve as an element of the X-ray tube andsimultaneously as 'an' element of the thermo-couple. Across-said anode'extension and said single wire is'electrically connected any suitably:calibrated indicating device'- which may'indicate the temperature of thetarget so' that the operatormay be informed as to its thermal condition.The indicator clevice'may consist of any standard form-ofany-appropriately calibrated 'millivoltmeter or galvan'ometer, the.constructional andxfunctionalfeatures of which arewell" known andform nopart of the present invention; 1 :1 r r i r One'of the objects oflourinvention is to provid'e an electric discharge device' embodying a;

thermo-couple which combination may be relatively readily, expeditiouslyand inexpensively manufactured.

Another object of our invention is. to provide an electric dischargedevice embodying a thermocouple thecombination of which is relativelysimple and attractive and consists of relatively few parts.

A still further object of our invention is to provide a relativelysimple and attractive X-ray tube having a thermc-couple associatedtherewith, which combination performs the function of an X-ray tube andhas a relatively sensitive thermogouple associated therewith.

Our invention finds application in a number of different types ofelectric discharges devices, but for the sake of. simplicity andconciseness, and

further, so that .the advantages attendant therer to may be readilyapparent, we will describe it as 20 .7

applied to an X-ray tube. Although the invention is applicable to most,if not all of the X-ray tubes, we will hereinafter describe itsapplication to the type of construction disclosed in the patentapplication of Nelson H. Stewart, Serial No. 578,244, filed December 1,1931, and assigned to the same assignee as the present invention. Theillustrative embodiment of the invention hereinafter described is to betaken by no meansin the way of limitation, but merely in a manner ofillustration. n

A clear understanding of our invention may be obtained from thefollowing description and appended drawing wherein;

Figure .1 represents an elevational view with some of the parts insection of an X-ray device embodying our invention;

Figure 2 is a cross section of Figure 1 along lines IIII of Figure 1 inthe direction of the arrows;

Figure 3 is similar to Figure 2 and represents a cross sectional view ofa modification of Figure 1; and

Figure 4 represents a modification of the anode and thermo-ooupleconstruction illustrated in Figure '1.

As shown in Figure 1 the X-ray tube therein illustrated may consist of aglass envelope having a body portion 11 of generally cylindrical form,with a hemispherical upper portion 12 at one end and a reentrant tube 13at its other end.

This reentrant tube 13 extends upwardly into the' body portion and has amajor portion thereof spaced therefrom. To the upper end of saidreentrant tube 13 is hermetically sealed a metallic tubular andpreferably copper sleeve or support coupling 14. Secured to the upperend of said support coupling 14 is an anode 16 measuring about one andone eighth inches in diameter and composed of copper or the like.

The support sleeve or coupling has means, and as shown a threadedrecess, in which is screwed a metallic and preferably a copper rod 15also about one inch in diameter, which ordinarily functions as a heatand electrical conducting element of the common X-ray tube.

The anode 16 and the anode extension 15'are in axial alignment, with theanode 16 being located in the evacuated spacewithin the envelope, andthe anode extension 15 being located outside of said envelope andextending substantially beyond the lower limit of the envelope.

' On to the free end of said anode extension 15 is secured by means of astud bolt or other advisable means a radiator 18 which as shown consistsof a plurality of aluminum fins. The upper or free sten or the like,serving as an X-ray emitting.

mamrial upon bombardment thereof by the electrons from a suitableelectron emitting filamentary cathode, (not shown).

Disposed around andhaving its interior wall 7 spaced from the free ortarget end of the anode 16 is an X-ray screen 20 composed of nickel-ironor the like. This X-ray screen houses both the cathode and a focusingcup (both not shown). The cathode is electrically connected to a plurality of conductors 21 and 22 which are hermetically sealed to theenvelope 10, and electrically secured to contact caps 23 and 24respectively located on the exterior of the envelope near thehemispherical end thereof.

Surrounding this metallic screen and functioning to provide a screensupporting and shock absorbing means are a plurality of resilient plates25 which bear against the outer surface of saidscreen and the interiorwall of the envelope.

Located within the envelope and extending upwardly therewithin is asecond reentrant tube 26 surrounding and spaced from the tubular sleeve14 and the anode 16. This reentrant tube is of a material length and hasits lower edge fusibly united with the envelope.

Secured to said anode may be a resilient sleeve such as that disclosedin the patent to Ulrey No. 1,715,152 issued May 28, 1929 and assigned tothe same assignee as the present invention, or as shown, resilientplates or spring means 45 such as those described by Blakeman in UnitedStates patent application Serial No. 560,738, filed September 2, 1931and assigned to the same assignee as the present invention.

An inverted cup shaped shielding means'27, M composed of copper or thelike, has its base resting upon the upper shoulder of the tubular member 14' and has a portion thereof located therebetween and the lower endof the anode 16. The cylindrical portion of this shield extendsdownwardly, surrounds and is spaced from the tubular sleeve 14, the sealand the upper portion of the reentrant tube portion 13.

According to our invention and as shown in Figures 1 and 2, We provide asimplified structure wherein the anode 1.6 serves as an electrode and aheat radiating means for the X-ray tube, and also as one of the elementsof an indicating means, and specifically a thermo-couple.

As illustrated the anode 16, at a position below and substantially inthevicinity of the target 19 is bored to provide a small diameter recess 28located adjacent said target. Extending longitudinally of the anode fromthe lower end thereof up to said recess 28 is a shallow, relativelynarrow groove 29 adapted to accommodate an element 30, which togethertherewith forms a thermo-couple, and adapted to receive also aninsulating sleeve 31 of quartz or the like, surrounding said element 30.The groove 29 may be readily formed by a simple milling operation.

The single wire 30 may be composed of any metal or alloy other thancopper, as for example nickel, nickel alloy and the like, having thedesired thermo-couple properties. The thermocouple wire 30 has arelatively short bent portion lid 33 extending about normal to the majorportion thereof and located in the recess 28. The remaining length ofwire contiguous therewith extends along the longitudinal groove, alongthe shield 27 and over to and through one side of the envelope near thelower portion thereof, wherein it forms an air tight seal therewith,with a portion thereof extending outside of the envelope.

This small portion of thethermo-couple wire extending outsidetheenvelopeis elctricallyse cured to a metallic cap 34 located on the exterior ofsaid envelope. In order that the bent portion extending within therecess maybe in close contact with the anode 16 and on that side of'there-. cess closest to the plane of the target there is provided a plug,peg or wedge 35 composed of the.

same-material as the anode, asfor'example copper.. This plug, pegorwedge maybe driven into the recess containing said bent portion of thethermo-couple wire and serves tofirmly locate one end of said wire andto force said. bent portion into good contact relation with-the anode toform a good thermo-junction. Any other desirable method or means offorming a good thermojunction between the anode 16 and the end 33 of.the thermo-couple wire 30 may be employed. The plug, peg or wedge 35 weregard as part of the anode; f In orderthat the anode and thethermo-couple wire may efiiciently function as a thermo-couple and toprovide an attractive structure, there is provided over thethermo-couple wire the di-electrio sleeve 31, as for example quartz orthe like.

This di-electric sleeve 31- totally surrounds that portion of the wireextending from the upper end of the groove andbelow the free end of theshield. As shown this (ii-electric shield has a bore of sufficient'diameter adapted to accommodate the thermo-couple wire '30 and anoutside diameter of such dimension as to fit snugly in said groove 29.

The thermo-couple wire 30, together with its dielectric sleeve 31, maybe readily fixed in the groove 29 of said anode 1-6 by any appropriatemeans and one means, as shown in Figure 1, comprises providing the anodealong appropriate lengths thereof with circular shallow grooves 36. Tiewires 37 of copper or the like are located in these grooves so as tofixedly secure said thermo couple wire 30 togetherwith insulation 31 tothe anode and thus prevent any liability of insulation fracture.Further, a tie wire 32 fixedly secures the insulated thermocouple wireto the shield 27, as shown in Figures- 1 and 4.

One other means that we have found suited for the purpose of fixing thethermo-couple wire 30 together with its insulation 31 to the anode isdisclosed in Figure 3. As therein disclosed there is obviated thenecessity of providing spacedcircular grooves on the surface of theanode to accommodate tie wires and also the tie wires themselves.

'As shown, for this purpose we may'provide a plurality of grooves 38 and39, forming a groove of dovetail form. The grooves 38 ing to ourinvention may replace the groove 29 illustrated in Figures 1 and2. Thegroove 38-extends longitudinally along the anode. U

Below said groove-38 and having its upper limit contiguous with thelower portion of the groove 38 is a shallow groove 39 of the samegeneral dimensions as the-groove 29'heretofore described in connectionwith Figures 1 and 2. In this con struction the thermo-couple wire 30together with its insulating sleeve 31 is located substantially withinthe lower groove 39.

A key 40, composed of a material preferably the same as that of theanode 16 and being of such a configuration and dimensions that it may besliddisplacement thereof and and 39 accord ably mounted in the; dovetailgroove38, is located in said groove 38 so that the anode appears to be asubstantially unitary, homogeneous structure. The key 40, assembledinsaid groove 38, frictionallyengages the outer surface ofv saidinsulating material 31 so as to holdor fix the same together with thethermo-couple wire, 30 ina relatively permanent position.

Although we; have described means, such as a key, 4001 thetie wires 3'7for fixing the thermocouple wire and insulating sleeve to the anode itis within the scope of this invention to include any means for holdingsaid thermo-couple wire and insulator to said anode. The invention'alsocontemplates forthis same general purpose the utilization of only thespringmeans 45. This spring means may be located between the anode 16and the second reentrant stem 26 sothat they are in frictionalengagementwith a portionv of the anode, the insulating covering 31 and the innersurface of the reentrant tube. Another embodiment of our invention isillustrated in Figure 4 andis essentially a-modification of theconstruction shown in Figure 1. As shown the anode thermo-coupleconstruction comprises an-anodesimilar to that illustrated in Figure 1,except that the-anode shown in Figure 4 has a small bore elongatedopening 50 extending I through approximately the center thereof with Athermo-couple wire 54 extending through a copperplug '56 whose externaldiameter is about the same diameter as that of the .bore 50 has one endthereof welded to said copper plug as at. 57,

which copper plug is firmly securedinthe closed end of the boret50 byany. appropriate pressure means.-- x

The copper plug 56 or other appropriate means for. forming agood thermalcontact between the anode. proper and the wire 56 we regard as. part ofthe anode 16. The thermo-couplewire extends throughthe bore. 50, the.large bore '52: and.

the side bore 53.. Surrounding saidthermo-couple wire are a plurality ofquartz lengths of tubing'55' which insulates from the anode thatportion. of

the thermo-couplev wire beyond thejunction.

It. has been found thata construction embodying the featureshereinbefore described may readily be associated with an appropriateindicating means so that the operator'maybecome cognizant of thetemperature ofthe target, at any time during the operation of said tube.The general hookup involved in associating an indicating devicetherewith is illustrated in Figure 1 andcomprises an electricalconductor connection 41 between an appropriate terminal of theappropriately .calibrated and shielded corona proof millivoltmeter42.and the radiator 18, and an electrical connection 43 between theother terminal of said meter to the cap 34. The shielded case iselectrically connected to the conductor 41 by a suitable conductor.

Although we have described with particularity our invention togetherwith its associated parts, it has been done only so that the inventionmay be readily practiced. The scope of the invention is to be limitedonly by the prior art.

What is claimed is: I

1. The combination of a thermo-couple and an electrical discharge deviceincluding an envelope, a plurality of electrodes therein, one of saidelectrodes being an element of the thermo-couple and having a groove inthe surface thereof, an electrical conducting element, difiering incomposition from that of said one of said electrodes,

secured to said one of said electrodes, and insu-' lating means in saidgroove between said ele-- ment and said one of said electrodes,a'thermojunction consisting of said one of said electrodes and saidelement, said one of said electrodes be ing the other element of thethermo-couple.

2. The combination of a thermo-oouple and an electrical discharge devicecomprising an envelope, a plurality of electrodes therein, one of saidelectrodes having a recess therein and a groove extending along thesurface thereof, and an ele ment differing in composition from that ofsaid one of said electrodes, said element having a portion thereof insaid recess and contiguous with said one of said electrodes andinsulating means in the groove between'said one of said electrodesandsaid element, said one of said electrodes and said element forming 'a'therino-jun'ction at the contiguous areas of said one of said electrodesand said element, said one of said electrodes and the elements of athermoa portion thereof contiguous witha portion of said element andforming a thermo-junction therewith, another portion of said elementlocated in said groove, insulating means between the surface of thegroove and said element lying there-' Within; said anode and saidelement being elements of the thermo-couple.

a. The combination of a thermo-couple and.

an electrical.discharge-device comprising an en-- closing envelope, ananode, a cathode, and an element therein, the =thermo-junctio-n of saidthermo-couple consisting of a portion of said element contiguous withsaid anode,'a groove in said anode, another portion of said element insaid groove, insulatingmeans between said element and the surface ofsaid groove'and means maintaining said element in said groove.

5. The combination of a thermo-couple and an X-ray, device'comprising anenclosing envelope including an anode, a' cathode and an element of acomposition other than that of the anode located therewithin, said anodeand a por-' tion of said element being contiguous to form athermo-junction, said element and said anode be? ing elements of thethermo-couple.

6. The combination of a thermo-couple and an X-ray tube comprising anenclosing envelope including a cathode, an anode and an element, saidelement being a metallic composition other than that of said anode, saidanode having a target portion, the thermo-junction of said thermocoupleconsisting of a portion'of said element contiguous with a portion ofsaid anode other than the target portion, said anode and said elementbeing elementsof the thermo-couple.

7; The combination of a thermo-couple and an X-ray device comprising anenclosing envelope including an anode, a cathode and an elementtherewithin, thecomposition of said element differing from that of saidanode, .said anode having a target portion the thermo-junction of saidthermo-couple consisting of a portion of said element contiguous withsaid anode at a position relatively close to said target, anotherportion of said element insulated from said anode, said anode and saidelement being elements of the thermo-couple; 8. The combination of athermo-couple and an X-ray tube comprising an enclosing envelopeincluding an anode, a cathode and an electrical conducting element, saidelement being of a composition other than that of the anode, said anodehaving a groove therein, a portion of said element being contiguous withsaid anode to form a thermo-junction, another portion of said elementlocated in said groove, an insulating sleeve on said element and in saidgroove, said element and said anode being elements of the thermo-couple.

-9. The combination of a therrno-couple and an Xray tube, comprisinganienclosing envelope, an anode,.a cathode and an element therewithin,said element being of a metallic composition other than that of theanode, saidpanode.

having a longitudinal groove in the face thereof, the thermo-junction ofsaid thermo-couple consisting of a portion of said element contiguouswith said anode, another portion of said element located in said grooveand insulated thereat from the anode and means maintaining said elementin position, said anode and said element being elements of thethermo-couple.

10. The combination of a thermo-couple and an X-ray tube comprising anenvelope, an anode, a cathode, and an element, said element being of ametallic composition other than that of said anode, said anode having agroove in the face thereof, said element having a portion thereofcontiguous with the anode to form a thermoiunction therewith, anotherportion of said element surrounded by refractory insulating sleevelocated'in said groove, said anode and said element being elements ofthe thermo-oouple.

ll. The combination of a thermo-couple and anX-ray tube comprising anenvelope having an anode, a cathode and an element therein, saidelementcomposed of a material other than that of said anode, said elementhaving a portion thereof contiguous with said anode, a longitudinalgroove extending along said anode, a refractory insulating sleevesurrounding another portion of said element and located in said groove,and still another portion of said-element sealed to said envelope, and akeyin the groove of said anode fixing the element and insulating sleevetherefor therewithin, said anode and-said element being elements of thethermo--couple.

v CLAYTON TRIDLE ULREY.

NORMAN C. BEESE.

